Iron Mining and Processing in South Africa

R E S O U R C E P A C K

Iron Mining and Processing in South Africa

Source: Kumba Iron Ore, www.kumba.co.za

UNIVERS I TY OF CAPE TOWNIDYUNIVES I TH I YASEKAPA • UNIVERS I TE I T VAN KAAPSTAD

Road construction / concrete

manufacture

Crushing

Open pit mining is used to excavate iron ore that is closeto the surface. The topsoil is removed and the ore isloosened by drilling and blasting. Haulage trucks movethe ore to stockpiles. From there a conveyor belt systemtransports the ore to the crushers at the processing plant.

Blending anddispatch

Blast furnace

Washing andscreening

Surface mining

Steelmanufacturing

Separation andclassification

Pig iron Slag

Iron Ore (65% Fe)

The ore undergoes aseries of crushing stepsto reduce the particlesize.

Iron ore is separated intothe different grades usingcyclones and drumseparators.

Coke (carbon) is reduced:2C + O2 2COCO reacts with iron ore to form iron:3CO + Fe2O3 2Fe + 3CO2Flux (limestone) is added to removeimpurities from the molten iron to formslag:CaCO3 CaO + CO2CaO + SiO2 CaSiO3 (slag)Molten slag floats on top of the molteniron.

Coke (C)

Limestone (CaCO3)

Hot Air

The blast furnace produces pig ironthat is sent to steel manufacturers.

The blast furnaceFeed of ore,

fluxingagents and

coke

Removalof slag

Tapping ofmolten pig iron

Collection ofwaste gases

Hot blastfrom Cowperstoves

carbon dioxide forms

carbon monoxideforms

iron formsColumn of ore

coke andfluxing agents(e.g. limestone)

Road construction / concrete

manufacture

Blending anddispatch

Washing andscreening

Surface mining

Steelmanufacturing

Phosphate Mining and Processing in South Africa

R E S O U R C E P A C K

Phosphate Mining and Processing in South Africa

Source: Roux et al. (1989). Phosphates in South Africa. J.S.Afr.Inst.Min.Metall. 89(5):129-139.

UNIVERS I TY OF CAPE TOWNIDYUNIVES I TH I YASEKAPA • UNIVERS I TE I T VAN KAAPSTAD

Open-pit mining(Foskor)

Drilling andblasting

Ore from PalaboraMining Company

(PMC)Primary crusher

Milling

Secondary andtertiary crushers

PhosphateFlotation

Tailings totailings dam

Filtration ofconcentrate

Dispatch to fertilizercompany or

processing plant

Add sulfuric acid to make super-phosphate (mixture of calciumphosphate and calcium sulfate)

Drying

Add phosphoric acid to maketriple-super-phosphate

Ore from PMC undergoes copper flotation to removecopper and magnetic separation to remove magnetite(iron) ore prior to phosphate flotation.

2Ca5(PO4)3F + 7H2SO4 3Ca(H2PO4)2 + 7CaSO4 + 2HF Ca5(PO4)3F + 7H3PO4 + 5H2O 5Ca(H2PO4)2 • H2O + HF

Super-phosphates and triple-super-phosphates are used as fertilizers

Drilling andblasting

Secondary andtertiary crushers

PhosphateFlotation

Drying

The phosphate mining process at Foskor receivesphosphate rock from two sources: The Foskor open-pitmine and the Palabora Mining Company

Gold Mining and Processing in South Africa

R E S O U R C E P A C K

Gold Mining and Processing in South Africa

UNIVERS I TY OF CAPE TOWNIDYUNIVES I TH I YASEKAPA • UNIVERS I TE I T VAN KAAPSTAD

Refining

Recovery:smelting

Comminution:crushing &

milling

South African gold mines are deep level minesreaching depths of over three kilometres. Miners gounderground in shaft cages and then walk or taketrains to the work face.

The oreundergoes aseries of crushingand milling stepsto reduce its sizefor furtherprocessing.

Gold is leached from the slurry by meansof dilute cyanide solution. Gold has ahigh affinity for cyanide solution. Thefollowing reaction occurs:

Ganguerock goesto thetailingsdam

Unwanted rock (gangue) isfiltered out and zinc dust isadded to precipitate thegold. Zinc displaces gold ina redox reaction. Impuritiessuch as silver, platinum,copper, lead and zinc alsoprecipitate out.

Carbon is used to adsorb goldfrom the solution. This is calledthe ‘carbon-in-pulp’ process andinvolves three phases:- Adsorption, where dissolved

gold is loaded onto aeratedcarbon

- Elution, where gold is removedfrom carbon by an alkalinecyanide solution

- Electrowinning, where gold isremoved & deposited onsteel cathodes

The gold is smelted in an electric furnace to producegold bars of 99 % purity.

Filtration& zinc

precipitation

Carbon-in-pulp& electro-winning

Flux is added and the gold is melted in a furnace toseparate the gold from the impurities. The flux willoxidise the impurities, which will float on top of themolten gold and can be removed. Gold of 99,99%purity is produced.

4Au + 8NaCN + O2 + 2H2O 4NaAu(CN)2 + 4NaOH

Ore is hoisted from the lowestunderground level of the mine in skipsand then transported to the surface byrail hoppers or conveyor belts.

Leaching:cyanidation

process

Undergroundmining

Leaching:cyanidation

process

Undergroundmining

Recovery:smelting

Extraction:removing goldfrom solution

Source: Chamber of Mines, www.bullion.org.za

Zn + 2NaAu(CN)2 2Au + Zn(CN)2 + 2NaCN

Coal Mining and Processing in South Africa

R E S O U R C E P A C K

Coal Mining and Processing in South Africa

Bord-and-pillar method(65% recovery)

Rib-pillar method(90% recovery)

Longwall mining(90% recovery)

Source: Anglo Coal video 2008; Powering South Africa the Anglo Coal way.

Primary crushing takes place whilethe coal is still underground.Conveyor belts then transport thecoal to the secondary and tertiarycrushers at the processing plant.

The coal arrives at the coalwashing plant by means of a seriesof conveyor belts.

The coal is separated into differentsizes, called grades.

The coalis dried,ready fortransport.

UNIVERS I TY OF CAPE TOWNIDYUNIVES I TH I YASEKAPA • UNIVERS I TE I T VAN KAAPSTAD

Surfacemining

Undergroundmining

Crushing

Washing

Separation andclassification

Drying anddispatch

Local market(75%)

Export market(25%)

Householduse(2%)

Electricitygeneration

(53%)

Metallurgicalindustries

(12%)

Petrochemicalindustries

(33%)

Opencast mining is used to excavateshallow-lying coal seams. These seams aredrilled and blasted prior to excavation.Shovels load the coal onto haul trucks, whichtake it to the tipping area. Conveyor beltstransport the coal to the processing plant.

Surfacemining

Undergroundmining

Washing

Drying anddispatch

Householduse(2%)

Electricitygeneration

(53%)

Metallurgicalindustries

(12%)

Petrochemicalindustries

(33%)